In conventional water tanks, various types of impurities and foreign materials are stacked in the bottoms of the insides of the water tanks during use, the water tanks become grounds for the propagation of bacteria because water residues remain along with the impurities when water is drained, and there are lots of difficulty and inconvenience with the complete cleaning of the insides of the water tanks.
Furthermore, in the conventional water tanks, a water filtering method is configured such that a hose and a filtering mesh are connected outside each of the water tanks, the hose and the filtering mesh are introduced into the water tank, and introduced water is passed through a separate filtering device. Accordingly, filtering efficiency is degraded, pressure is reduced or a motor breaks down frequently due to a burden imposed on an apparatus, and the rate of occurrence of industrial accidents is also high due to the manual performance of filtering work.
Furthermore, when a cleaning agent (a liquid chemical) is used for complete cleaning during the cleaning of the inside of the water tank, a residue cleaning fluid component remains inside the water tank, and thus a plurality of problems occur in that the residue cleaning fluid component acts as a factor which damages health and an environment, etc.
In order to overcome the above-described problems, preceding Korean Patent No. 10-0802602 entitled a multi-purpose universal water tank discloses a technology for providing a multi-purpose water tank in which a filtering part capable of filtering out various types of impurities or foreign materials is installed in the lower portion of the water tank and a backwashing means is provided to clean the impurities filtered out by the filtering part.
However, the impurities filtered out by the filtering part installed in the conventional water tank cannot be completely eliminated, a problem with the filtering of water occurs due to the continuous adsorption of foreign materials onto the filtering part in the case of the long-term use of the water tank, and a problem occurs in that usability is degraded because it is difficult to replace and repair the filtering part.